1. Field of the Invention
The present invention relates to a tongue plate slidably fitted on a safety seat belt for preventing a seat occupant of the motor vehicle from being thrown out of his seat upon the occurance of an accident or collision, and particularly to such a tongue plate for the safety seat belt which comprises a continuous webbing which consists of a lap belt and a shoulder belt.
2. Description of the Prior Art
In recent years for restraining movement of a seat occupant of a motor vehicle, there has been generally used a safety seat belt comprising a continuous webbing including a lap belt and a shoulder belt.
In the tongue plate applicable for use with such a safety seat belt of the foregoing type, there is provided an opening for locking engagement with a buckle on one end thereof and a slotted opening providing for the passage of the continuous webbing therethrough on the other end thereof. In the slotted opening providing for the passage of this webbing, there has been defined some frictional resistance to the passage of this webbing to reduce the wind-up force of a retractor applied to the webbing on opposite sides of the retractor through the slotted opening.
On the other hand, as in the case of such a tongue plate, slack of the shoulder belt has been usually made equal to that of the lap belt because frictional resistance corresponding to movement of the tongue plate in the direction of the shoulder belt is equivalent to that corresponding to movement of the tongue plate in the direction of the lap belt. This has caused unnecessary slack of the lap belt portion, and also helped to restrain movement of the shoulder belt portion needlessly. Furthermore, since frictional resistance of such a tongue plate becomes large, a strong force has to be applied to the tongue plate in view of movement of the seat occupant when setting the safety seat belt. This causes the tongue plate in locking engagement with the buckle to produce swinging movement centered on the buckle anchor. Therefore, there have been some disadvantages that the tongue plate provides pressure upon the seat occupant's side and chest or the like due to such a swinging movement thereof.